As an interface device between a solar power generation system and a power grid, a photovoltaic grid-connected inverter has a heat dissipation performance which significantly affects the working stability of the entire inverter system, the service life of the power device and the volume of the product. Internal components of the inverter include high-protection grade power devices such as a reactor, a resistor and a heat sink, and low-protection grade power devices such as an inverting module, a capacitor, a DC (direct current) air switch component, an AC (alternate current) capacitor, an AC breaker and an AC contactor.
Considering the power loss characteristics and economy of the high-power grid-connected inverters, most of the high-power grid-connected inverters adopt forced air cooling to dissipate heat, that is, all the devices inside the inverter are placed in cold air.
The cooling medium for the above forced air cooling is outside air with room temperature, and when the inverter is in a harsh environment, outside cold air blows into the inverter, the contaminated cold air therein is apt to damage the devices inside the inverter, particularly some low-protection grade devices such as the circuit board, resulting in a decreased overall protection grade of the inverter and affecting the service life of the inverter.
In summary, a technical issue to be addressed urgently by those skilled in the art is to improve the overall protection grade of the inverter.